[JENA-1455] QueryBuilder allows Node_Variable instances into QueryTripleIterator

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: Jena 3.6.0
• Fix Version/s: Jena 3.7.0
• Component/s: QueryBuilder
• Assignee: Claude Warren
• Reporter: Claude Warren
• Created: 26/Dec/17 23:10
• Updated: 04/Jan/24 15:24
• Resolved: 27/Dec/17 08:22

Description

Using Node_Variable instances in Quads and Triples to to methods results in Node_Variable instances appearing in the QueryTripleIterator.

QueryTripleIterator at line 87 calls Var.isVar(node) which throws an exception if the node is a Node_Variable. But based code following line 87 I think that Node_Variable should be accepted.

        private static Node substitute(Node node, Binding binding)
        {
            if ( Var.isVar(node) ) // <---- line 87
            {
                Node x = binding.get(Var.alloc(node)) ;
                if ( x != null )
                    return x ;
            }
            return node ;
        }

QueryTripleIterator is internal code and is only expecting Var instances. The solution is to fix the QueryBuilder code so that it only produces Var in the queries resulting from a build() execution.